1. Field of the Invention
The present invention relates to a recording medium, and also to a recording apparatus and a reading apparatus compatible with such a recording medium.
2. Description of the Related Art
As a recording medium, a compact disc (CD) is known. Various types of CD-format discs, such as compact disc digital audio (CD-DA), compact disc read only memory (CD-ROM), compact disc recordable (CD-R), compact disc rewritable (CD-RW), and CD-TEXT, all of which belong to the so-called xe2x80x9cCD familyxe2x80x9d, have been developed and are commonly used.
The CD-DA and CD-ROM are read only, while the CD-R is a write-once medium using an organic pigment on a recording layer, and the CD-RW is a rewritable medium using a phase change technique.
On such CD-format discs, data, such as music, video, and computer data, are recorded, and also, track numbers, indexes, and addresses are recorded as sub-codes.
The track number is a number representing a piece of music (track). The indexes are units which form a track, for example, units which partition the movements of a track.
The addresses include absolute addresses represented by consecutive values covering the whole disc and relative addresses represented in units of tracks (which are also referred to as xe2x80x9cprogramsxe2x80x9d represented in units of pieces of music). Accordingly, by extracting sub-codes, the absolute address and the relative address at each position of a disc can be identified.
The address is represented by a time value, such as minute/second/frame. Thus, in the CD format, the xe2x80x9ctimexe2x80x9d can be synonymous with the xe2x80x9cposition (address)xe2x80x9d, for example, the xe2x80x9cabsolute timexe2x80x9d corresponds to the xe2x80x9cabsolute addressxe2x80x9d.
For example, in the CD format, the sub-code address is represented by minute/second/frame, each having eight bits. Since the eight-bit address is represented in binary coded decimal (BCD), it can express a range from 0 to 99. Accordingly, the xe2x80x9cminutexe2x80x9d can be designated from 0 to 99 minutes. However, the xe2x80x9csecondxe2x80x9d is inevitably expressed from 0 to 59, and the xe2x80x9cframexe2x80x9d is expressed from 0 to 74 since 75 frames, such as frame 0 to frame 74 are defined in the CD format.
On the innermost portion of a disc, sub-code information, such as table-of-content (TOC) information, is recorded. The TOC information indicates an address representing the head and the extent of each track. The content of the address (type of address) can be identified by point information.
For example, if the point information designates a special value, the information described in the corresponding sub-code frame indicates the start address of each track or the first/last track number rather than the absolute address or the relative address.
In recordable discs, such as a CD-R and a CD-RW, a recording track is formed by wobbling grooves. The wobbling waveforms of the grooves are formed by modulating waveforms based on the absolute address information, and thus, the absolute addresses can be identified by the wobbling information of the grooves. Since sub-codes are not yet recorded on a disc without recorded data, the address information is read by the wobbling groove when data is recorded.
In addition to the above-described various types of CD-format (CD-standard) discs, larger capacity discs with high density are being developed, and discs having a plurality of areas whose physical characteristics are different, which are referred to as xe2x80x9chybrid discsxe2x80x9d, are also being developed. The variety of the materials and configurations of discs is also being increased.
Under these circumstances, in order to achieve sufficient recording and reading performance of a recording apparatus and a reading apparatus, it becomes necessary to optimize various settings in accordance with the physical characteristics of a loaded disc. For example, the servo gain, laser power, and access range should be optimized.
It is, however, difficult to sufficiently determine the physical characteristics of the individual discs loaded in a recording apparatus or a reading apparatus. Certain calibration may be performed when a disc is loaded, and even so, it is still difficult to precisely determine the physical characteristics of the loaded disc. Additionally, since the burden is increased by the calibration operation, the amount of software and hardware must be increased, and also, it takes a longer time before a recording or reading operation is started.
Accordingly, there is still a demand for easy and precise determination of the physical characteristics of discs without impairing the compatibility with known CD-format discs or increasing the complexity of hardware and software used in a recording apparatus and a reading apparatus.
Accordingly, in view of the above background, it is an object of the present invention to easily and precisely determine the physical characteristics of recording media while being compatible with various types of recording media and maintaining the compatibility with known recording media.
In order to achieve the above object, according to one aspect of the present invention, there is provided a recording medium including main data and a sub-code recorded therein. Physical characteristic information of the recording medium is recorded within the sub-code.
Point information representing content types of predetermined information may be disposed within the sub-code, and the physical characteristic information may be recorded in correspondence with specific values of the point information.
The physical characteristic information may be recorded within the sub-code of a lead-in area.
The physical characteristic information may include information concerning the material, the type, the linear velocity, the track pitch, the moment of inertia, the configuration, or the size of the recording medium.
According to another aspect of the present invention, there is provided a recording medium for storing main data and a sub-code. The recording medium includes a plurality of recording/reading unit areas whose physical characteristics are different, each of the recording/reading unit areas consisting of a lead-in area, a program area, and a lead-out area. In the sub-code of the lead-in area of each of the recording/reading unit areas, physical characteristic information of the corresponding recording/reading unit area is recorded, and start position information indicating a position at which the lead-in area of the subsequent recording/reading unit area starts is recorded.
In the sub-code of the lead-in area of each of the recording/reading unit areas, end position information indicating a position at which the lead-out area of the corresponding recording/reading unit area ends may be recorded.
According to still another aspect of the present invention, there is provided a recording apparatus compatible with a recording medium which stores main data and a sub-code, physical characteristic information of the recording medium being recorded within the sub-code. The recording apparatus includes a determining unit for determining physical characteristics of the recording medium by reading the physical characteristic information from the sub-code. A recording control unit performs settings for a recording operation according to the physical characteristics determined by the determining unit and then allows the recording operation to be performed.
According to a further aspect of the present invention, there is provided a recording apparatus compatible with a recording medium which stores main data and a sub-code, the recording medium including a plurality of recording/reading unit areas whose physical characteristics are different, each of the recording/reading unit areas consisting of a lead-in area, a program area, and a lead-out area. In the sub-code of the lead-in area of each of the recording/reading unit areas, physical characteristic information of the corresponding recording/reading unit area is recorded, and start position information indicating a position at which the lead-in area of the subsequent recording/reading unit area starts is recorded. The recording apparatus includes an access control unit for determining the position of the lead-in area of the subsequent recording/reading unit area from the start position information recorded in the lead-in area of the current recording/reading unit area, and for allowing access to the determined position. A determining unit reads the physical characteristic information from the lead-in area of each of the recording/reading unit areas in accordance with the access controlled by the access control unit, and determines the physical characteristics of the corresponding recording/reading unit area. A recording control unit performs settings for a recording operation for each of the recording/reading unit areas according to the physical characteristics determined by the determining unit, and allows the recording operation to be performed.
According to a yet further aspect of the present invention, there is provided a reading apparatus compatible with a recording medium which stores main data and a sub-code, physical characteristic information of the recording medium being recorded in the sub-code. The reading apparatus includes a determining unit for determining physical characteristics of the recording medium by reading the physical characteristic information from the sub-code. A reading control unit performs settings for a reading operation according to the physical characteristics determined by the determining unit and allows the reading operation to be performed.
According to a further aspect of the present invention, there is provided a reading apparatus compatible with a recording medium which stores main data and a sub-code, the recording medium including a plurality of recording/reading unit areas whose physical characteristics are different, each of the recording/reading unit areas consisting of a lead-in area, a program area, and a lead-out area. In the sub-code of the lead-in area of each of the recording/reading unit areas, physical characteristic information of the corresponding recording/reading unit area is recorded, and start position information indicating a position at which the lead-in area of the subsequent recording/reading unit area starts is recorded. The reading apparatus includes an access control unit for determining the position of the lead-in area of the subsequent recording/reading unit area from the start position information recorded in the lead-in area of the current recording/reading unit area, and for allowing access to the determined position. A determining unit reads the physical characteristic information from the lead-in area of each of the recording/reading unit areas in accordance with the access controlled by the access control unit, and determines the physical characteristics of the corresponding recording/reading unit area. A reading control unit performs settings for a reading operation for each of the recording/reading unit areas according to the physical characteristics determined by the determining unit and allows the reading operation to be performed.
Thus, according to the present invention, in sub-code, the physical characteristics of the recording medium are recorded. By reading the sub-code, a recording apparatus and a reading apparatus can easily and accurately determine the physical characteristics of the disc.
It is thus possible to provide settings suitable for the recording operation and the reading operation, for example, the servo gain, the laser power, the laser driving waveform, the access range of the optical pick-up, thereby enhancing the recording and reading performance according to the type of disc.
The physical characteristics of the recording medium are not determined by a calibration operation. Theoretically, therefore, they can be determined with 100% precision, and the time required for starting the recording or reading operation can be shortened.
Additionally, since the physical characteristic information is recorded in correspondence with specific values of the point information within the sub-code, the compatibility with known format discs can be maintained. The physical characteristic information is recorded in the sub-code of the lead-in area, which is first read when a disc is loaded, thereby enabling a recording apparatus or a reading apparatus to easily and speedily obtain the physical information.
The material information of the recording medium is also included in the physical characteristic information. It is thus possible to optimize various settings for, for example, the laser power and the laser driving waveform, in accordance with the material.
Since the information, such as the medium type, the linear velocity, and the track pitch, is included in the physical characteristic information, the servo system for the recording/reading operation can be easily set, and the disc type can be easily determined.
The moment-of-inertia information and the disc configuration/size information are contained in the physical characteristic information. Accordingly, the spindle servo gain and the access range of the optical pick-up can be precisely set.
As to a disc having a plurality of unit areas (hybrid disc) whose physical characteristics are different, access can be easily made from the lead-in area of a unit area to the lead-in area of the subsequent unit area. Accordingly, a recording apparatus or a reading apparatus is able to easily and speedily read the physical characteristics information of each of the unit areas, which can be used for settings for a subsequent recording or reading operation. That is, it is possible to perform optimal settings according to the physical characteristic of each unit area, thereby enhancing the recording and reading performance.
In the sub-code of each unit area, the end position information of the lead-out area of the corresponding unit area is recorded. Accordingly, any gap between the lead-out area of the corresponding unit area and the lead-in area of the subsequent unit area can be correctly determined.